One of the major problems facing researchers in the area of neuropsychiatric disorders, such as schizophrenia and dementia of the Alzheimer's type (DAT) has been the lack of adequate animal models for these disorders. Without animal models any investigation into the pathophysiology of psychosis and dementia is extremely difficult. Since the symptoms of schizophrenia and DAT are primarily linguistic and cognitive, it is not surprising that animal models have not been developed for these disorders. However, there are non-linguistic methods which measure brain function related to cognition. Perhaps the most quantifiable and extensively studied (in both human and non-human primates) of these methods is the measurement of eye movements. A variety of eye movement abnormalities have been identified in patients with schizophrenia, as well as in patients with DAT. The purpose of this project is to provide the clinical data on eye movement abnormalities in schizophrenia and DAT from which a non-human primate model could be developed. In order to do this it is essential that the eye movement tasks be simple and well characterized, and that the measurement of eye movement be highly quantifiable.